This invention relates to hydraulic shock absorbers of the kind comprising a piston slidable in a cylinder, the piston having valves which permit flow between opposite sides of the piston while imposing a pressure drop on such flow to produce the damping effect.
In many previously known designs of shock absorbers of this kind, such as that shown in my U.S. Pat. No. 3,447,644, issued June 3, 1969, and entitled "Displacement Conscious Telescopic Shock Absorber," the valves which control flow in the two directions are arranged on opposite sides of the piston, with the valve seats both being formed by part of the piston. With this arrangement, it is necessary to provide two sets of flow passages through the piston; flow in one direction through the piston passes through one set of passages, while flow in the other direction passes through the other set. The drilling of these holes tends to increase the cost of manufacturing the piston. In addition, with many of the previous designs of shock absorber, the passages are arranged at an angle to the axis of the piston; this complicates the drilling process, and also makes it difficult to use alternative methods of manufacture such as sintering.
It is an object of the present invention to provide a shock absorber in which the piston needs only a single set of flow passages.
It is a further object of the present invention to provide a shock absorber in which the flow passages in the piston are arranged parallel to the piston axis.
It is a further object of the present invention to provide a shock absorber in which the valve arrangement allows a small flow in one direction with practically no pressure drop.
It is a further object of the invention to provide a shock absorber in which the valve arrangement consists of a single pack of valve discs attached to the piston.